modifying the source code for super mario wars wii

ok, so i prefer not to use any SD card at all in my wii, instead i have a 160g ext hdd, with a 5g fat partition. this has worked out great up until i tried using the super mario wars HB. the issue seems to be that the program looks for SD:\smw\.... and i want it to look for USB:\smw\.... doing a little search of the source code at googlecode found me the line in the source that calls that directory. I understand the basics of programming, but cant actually program... is there a quick and dirty way to make that change and recompile the source?